1. Field of the Invention
The present invention relates to an end equipment and a router, and in particular to an end equipment and a router which execute a destination address resolution of a data packet.
In recent years, a Non-Broadcast Multi Access (hereinafter abbreviated as NBMA) network represented by an ATM (Asynchronous Transfer Mode) network has numerously come into use for a network environment centering around a Distance Carrier and a network provider. In the mechanism of a data transmission a connection type of the NBMA network is quite different from a connectionless type broadcast network such as an Ethernet and the like. However, in either of both networks, an address resolution protocol (hereinafter referred to as ARP protocol) is required for recognizing a data link layer address each hardware has from a network layer logical address of a destination end equipment to which a packet is transmitted.
2. Description of the Related Art
In general, an end equipment or apparatus is connected to a LAN which is a subnetwork, and LAN""s are mutually connected with a router which is a relaying or repeating equipment to form an enterprise network, a campus network and the like.
When the end equipments communicate with each other within the same subnetwork, it is possible to transmit a packet directly to a destination end equipment. However, the end equipments in different subnetworks transmit the packet to a router at the boundary of the subnetworks for the direct transmission. The router which has received the packet determines to which router the packet should be transmitted in order to deliver the packet to the destination end equipment and transfers the packet to the next router. In this way, it also becomes possible to communicate with the end equipments in the different subnetworks.
It is to be noted that the end equipment transmits the packet by a transmission processor in an OS (operating system). The OS has an address list of the network, which can be reached from itself, as a routing table. In each of table entries, a destination IP address, its own output interface, a gateway address and the like are written.
The gateway address indicates the IP address of the router to which the packet is to be sent next, in order to send the packet to a destination end equipment in a subnetwork other than the home subnetwork. When the destination is for the same subnetwork, not the IP address of the router but that of the destination end equipment or its own IP address is set for the gateway address.
In addition, the OS holds an ARP table for a data link layer whereby a network layer address corresponds to a data link layer address.
When the packet is inputted including the destination address designated by the network layer address, for instance, the IP address (hereinafter referred only to the IP address), the transmission processor retrieves the routing table with the destination IP address as a key, and obtains the output interface and the gateway address.
When the destination end equipment is in the same subnetwork, the transmission processor retrieves the ARP table corresponding to the output interface to obtain a hardware address corresponding to the IP address for the communication. When the destination end equipment is in another subnetwork, the transmission processor retrieves the ARP table with the address of a gateway router obtained from the routing table as a key.
When no entry is found in the ARP table, the OS makes a MAC address demand for the destination IP address to all of the end equipments within the same subnetwork by using an ARP protocol. The MAC address having been obtained, it becomes possible to make the end equipment communicate with the router.
For instance, the ARP table which the end equipment in a conventional Ethernet in the broadcast network holds, where the IP address corresponds to the MAC address, enables the recognition of the MAC address from the IP address of the end equipment or the gateway which can be reached directly, as well as the communication between the end equipment and the router by using this MAC address.
In addition, the ARP protocol inquires the MAC address which is the data link layer address of all of the end equipments in the network by broadcast to obtain the same.
FIGS. 15 and 16 show examples of a conventional ARP protocol. In these examples, protocols on an ATM network which has been often used especially in recent years as an example of an NBMA network are shown. Over an ATM network 10, subnetworks 20_1-20_3 (hereinafter occasionally referred to as xe2x80x9c20xe2x80x9d in general) are provided, and the subnetworks 20_1, 20_2 are mutually connected with a router 30_1 and the subnetworks 20_2, 20_3 are mutually connected with a router 30_2. Also, the subnetworks 20_1, 20_3 are connected to end equipments 40_1, 40_2 (hereinafter occasionally referred to as xe2x80x9c40xe2x80x9d in general).
FIG. 15A shows an example of an ATM_ARP (ATM Address Resolution Protocol; hereinafter referred to as ATM_ARP protocol). In this example, the subnetwork 20 is a logical subnetwork (LIS: Logical IP Subnetwork) in a network layer. To the subnetwork 20_1 is further connected an end equipment 40_3 and to each logical subnetwork 20 are connected ATM_ARP servers 31_1-3 (hereinafter occasionally referred to as xe2x80x9c31xe2x80x9d in general).
The ATM_ARP protocol is designed to achieve an equal function to an ARP protocol on an ATM-LAN. Namely, it is the ARP protocol in an IPoverATM which carries out the transfer of an IP packet by using an ATM connection, provided between the end equipments by an ATM address instead of the MAC address, especially an SVC (Switched Virtual Connection).
In operation, first of all, each of the end equipments 40 registers its own IP address and ATM address in the ATM_ARP server which manages itself.
Sending a data packet addressed to the end equipment 40_2 of a different logical subnetwork 20_3 where no connection is established, the end equipment 40_1 sends an ARP request packet in which the destination IP address is added to the ATM_ARP server 31_1.
The ATM_ARP server 31_1 returns an ARP response packet including the ATM address of a next hop router 30_1 to the end equipment 40_1. The end equipment 40_1 transfers the packet to the router 30_1, which executes the address resolution by the ATM_ARP server 31_2 to transfer the packet to the router 30_2.
The router 30_2 recognizes the ATM address of the end equipment 40_2 by sending the ARP request packet to the ATM_ARP server 31_3, and completes the communication by sending the data packet to the end equipment 40_2.
Since there is originally no concept of broadcast in the NBMA network 10, it is impossible to make any inquiry by broadcast. Therefore, by preparing the ATM_ARP server 31, the ATM_ARP protocol executes a registering management of the ATM address for the end equipment within each of the logical subnetworks 20 to execute the address resolution. Each of the logical subnetworks 20 corresponds to an area, on the NBMA network 10 of the end equipment, of which each of the ATM_ARP servers 31 is in charge.
Namely, the logical subnetwork 20 is logically made over the ATM network 10 which can be communicated only with the. ATM address which is the address of the data link layer. Therefore, if only the ATM address of the end equipment 40_2 of the destination is recognized even when the communication is provided over the different logical subnetworks 20, using this address enables a source end equipment 40_1 to set up a VC (Virtual Connection) which is a direct path to the destination end equipment and to directly transmit the packet.
However, since the ATM_ARP protocol has to provide the packet communication over the logical subnetworks 20 through the router, the direct path connection between the end equipments which the original ATM network can provide cannot be set up.
As a protocol which provides a mechanism of the direct path connection, there is an NHRP (Next Hop Resolution Protocol; hereinafter referred to as NHRP protocol) proposed in an IETF (Internet Engineering Task Force).
FIG. 15B shows an example of the NHRP protocol. This example is different from the ATM_ARP protocol in FIG. 15A in that the ATM_ARP server 31 is not connected to the each of the logical subnetworks 20 and each of the routers 30_1-30_3 forms an NHS (NEXT Hop Server; hereinafter referred to as NHS server) in principle, which also works as a router.
First of all, each end equipment 40 registers its own IP address and ATM address in the NHS server 30 of the LIS to which each end equipment 40 belongs respectively.
Receiving the packet addressed to the end equipment 40_2 of the different logical subnetwork 20_3, the end equipment 40_1 transmits an NHRP resolution request packet, in which the IP address of the end equipment 40_2 is written, to the NHS server 30_1.
Since the destination IP address is not for the end equipment within the same subnetwork which the NHS server 30_1 manages, the NHS server 30_1 which has received the NHRP resolution request packet transfers it to the next NHS server 30_2 according to the routing table. The NHS server 30_2 determines that the destination IP address is for the logical subnetwork 20_3 under its management, retrieves the table of the ATM address (not shown) which the end equipment within the managed logical subnetwork holds, and transmits an NHRP resolution response packet including the ATM address of end equipment 40_2 to the end equipment 40_1 of a transmitting source of the resolution demand when there is an entry to hit.
The end equipment 40_1 recognizes the ATM address for the destination IP address from the NHRP resolution response packet, and by using this address a direct virtual connection (VC; referred to as a direct path) 62 is set up to the end equipment 40_2. Since the direct path 62 does not go through the NHS server 30, it becomes possible to have a communication at high speed without influences of a delay of the packet reconstruction in the NHS server 30, a transfer delay or the like.
Namely, the NHRP protocol is thought to be a technique of the ATM_ARP protocol expanded even to the end equipment in a different logical subnetwork.
It is to be noted that although the end equipment 40_1 transmits the data packet inputted before the direct path 62 is set up by using a hop-by-hop path 60 which goes through the routers 30_1, 30_2 after the direct path 62 is set up the end equipment 40_1 transmits the data packet through this path 62.
FIG. 16 shows an example of an RISP (Responder Initiated Shortcut Path) proposed in the Japanese patent application No. 9-41159. In this example, it is different that the routers 30_3-5 do not include an NHS server function, compared with the NHRP protocol in FIG. 15B.
The method of setting up the direct path between the end equipments 40_1 and 40_2 will now be described as follows:
The end equipment 40_1 receives the data packet addressed to the end equipment 40_2, prepares a call back request packet including its own ATM address, and transmits this packet to the end equipment 40_2 via a routing route 60 via the router.
The end equipment 40_2 calls the direct path by using the ATM address of the end equipment 40_1 included in the received packet, and resends a call back response packet including its own ATM address via the virtual connection 62 which has already been set up.
Namely, the address resolution and the direct path setting are executed at the same time. The end equipment 40_1 transmits the IP packet addressed to the subsequent end equipment 40_2 via the direct path.
FIG. 17 shows an example of a conventional ATM_ARP. In this example, the communication over the subnetworks through the router is not shown, different from the ATM_ARP shown in FIG. 15A, and the subnetworks (LIS1-LIS3) 20_1-3 are connected to output interfaces atm0-atm2 of the end equipment 40_1, respectively. The end equipments 40_2-40_5 are further connected to the subnetwork 20_1.
The IP addresses of the subnetworks 20_1-20_3 are xe2x80x9c133.160.115.0xe2x80x9d, xe2x80x9c133.160.114.0xe2x80x9d, and xe2x80x9c133.160.113.0xe2x80x9d, respectively. The IP address of the output interface atm0 of the end equipment 40_1 is xe2x80x9c133.160.115.3xe2x80x9d, and the IP addresses of the end equipments 40_2-40_5 are xe2x80x9c133.160.115.10xe2x80x9d, xe2x80x9c133.160.115.21xe2x80x9d, xe2x80x9c133.160.115.33xe2x80x9d, and xe2x80x9c133.160.115.47xe2x80x9d, respectively.
FIG. 18 shows a routing table 44 the end equipment 40_1 shown in FIG. 17 holds in the network layer and an ATM_ARP conversion mechanism 51 the data link layer holds.
The ATM_ARP conversion mechanism 51 comprises interface structures 52_1-52_4, an ATM_ARP table 54, and a VC (Virtual Connection) structure 53.
The operation of the end equipment 40_1 will now be described referring to FIG. 17 and FIG. 18 as follows: An IP protocol processor 55 of the end equipment 40_1; {circle around (1)} receives a data packet 70 addressed to the end equipment 40_2 whose IP address is xe2x80x9c133.160.115.10xe2x80x9d; {circle around (2)} retrieves the routing table 44 with the IP address xe2x80x9c133.160.115.10xe2x80x9d as a key, retrieves again with xe2x80x9c133.160.115.0xe2x80x9d to which a subnet mask xe2x80x9c255.255.255.0xe2x80x9d is applied because there is no hit, and recognizes the output interface xe2x80x9catm0xe2x80x9d; {circle around (3)} obtains the ATM address xe2x80x9c47.0091811  . . . CE.00xe2x80x9d of the destination end equipment by the retrieval of the ARM_ARP table which xe2x80x9catm0xe2x80x9d has with the IP address xe2x80x9c133.160.115.10xe2x80x9d as a key; {circle around (4)} obtains a VC number=xe2x80x9cVPI=0, VCI=32xe2x80x9d from the VC structure 53; and {circle around (5)} transmits the data packet 70 to the VC.
Moreover, when {circle around (1)} receiving the packet whose destination IP address is xe2x80x9c140.151.120.5xe2x80x9d, {circle around (6)} the IP protocol processor 55 hits the point-to-point type interface xe2x80x9ctun0xe2x80x9d (not shown), and {circle around (7)} transmits the packet to the interface xe2x80x9ctun0xe2x80x9d.
When there is an entry but no VC in the ATMARP table 54, the packet is transmitted after the VC is prepared based on the entry ATM address xe2x80x9c47.009181  . . . CE.00xe2x80x9d.
The address resolution and the data packet transmission in the conventional end equipment are summarized as follows:
{circle around (1)} In the ARP protocol, the end equipment inquires the MAC address which is the data link layer address of all of the end equipments within one subnetwork by broadcast. Therefore, the end equipment can achieve the address resolution only by the function of the data link layer regardless of the IP protocol in the network layer.
{circle around (2)} In the ATM_ARP protocol in the NBMA network composed of one logical subnetwork, the end equipment transmits an inquiry packet via the VC set up in the ATM_ARP server for the address resolution. The end equipment can achieve the address resolution only by the function of the data link layer.
{circle around (3)} In the ATM_ARP protocol in the NBMA network composed of a plurality of logical subnetworks, the end equipment has to communicate over logical subnetworks via the router. Therefore, both of the functions of the data link layer and the network layer are required for the address resolution.
{circle around (4)} In the NHRP protocol, the end equipment requires a routing function which is a network layer function for the address resolution and a function of the data link layer which converts the network layer address into the data link layer address.
{circle around (5)} In the RISP, the end equipment is composed so as to require the routing function of the network layer which transmits the call back request packet and not to require an address conversion mechanism of the data link layer.
Namely, in the ARP protocol of the above {circle around (1)}, {circle around (2)}, the end equipment is formed peculiar to the type of the data link layer as the ARP and ATM_ARP exist in the Ethernet. Accordingly, the development of an exclusive ARP function is required for the introduction of a new data link layer, which leads to an increase in cost for the development.
In the above {circle around (3)}, {circle around (4)}, and {circle around (5)} , the end equipment requires the routing function for the address resolution in the network layer and the address conversion function of the data link layer. In addition, a connection type NBMA network and a broadcast network of the Ethernet or the like which is a connection less type network are completely different from each other as to a data transmission mechanism, and a address conversion mechanism which converts the network layer logical address of the data packet transmission to the data link layer address.
Also, in the same NBMA network, the conversion mechanism is different depending on whether the area where data link layer address can be recognized should be limited only to a logical subnetwork or extended to the NBMA network in its entirety.
Accordingly, there is no portability between the protocols because the network layer and the data link layer are too closely related to be divided.
It is accordingly an object of the present invention to provide an end equipment, which execute a destination address resolution of a packet, which provides a packet transmitting system and an address resolution protocol which can be all processed in the network layer regardless of the difference between the NBMA network and the broadcast network and the difference between one logical subnetwork and a plurality of logical subnetworks for the area of the address resolution in the NBMA network, and which has a good portability.
[1] To achieve the above-mentioned object, an end equipment according to the present invention, referring to FIG. 1, comprises; an interface manager 42 which prepares a logical interface 47, provided between a network layer and a data link layer, corresponding to a direct route or a routing route, a routing table 44 indicating a corresponding relationship between a network layer address of a destination of an input packet and the logical interface, a packet transmitter 43 which transmits the input packet to the logical interface referring to the routing table 44 with the network layer address as a key, and a path manager 45 which transmits both of an inquiry packet for inquiring a data link layer address of the destination and the input packet to a preset logical interface 47 of the routing route when the logical interface for the direct route of the input packet is not registered in the table and which registers the logical interface the interface manager has established in the routing table 44 by demanding the interface manager 42 to prepare the logical interface for the direct route based on the data link layer address of the destination included in a received response packet.
In operation, the packet transmitter 43 in a source end equipment (including the router or a terminal equipment) receives an input data packet 70 from an upper layer, and retrieves the routing table 44 by a signal 81 with the network layer address of a destination end equipment as a key. As a result of the table retrieval, when there is found no direct route to directly reach the destination end equipment which belongs to the same or a different subnetwork, the packet transmitter 43 transmits the data packet 70 by a signal 82 to the logical interface of the routing route included in the interface 47 and notifies the path manager 45 that there is no direct route by a signal 84.
The path manager 45 includes its own data link layer address and network layer address, prepares an inquiry packet 95 for inquiring the data link layer address of the destination end equipment, and transmits it to the logical interface of a preset routing route. The data packet 70 and an inquiry packet 83 having been transmitted to the logical interface are transmitted to a router by a method which is suitable for each of the data link layers.
The path manager 45 which has received response packets 90, 91 for the inquiry packet via the interface 47 from the destination end equipment recognizes the data link layer address and the network layer address of the destination end equipment included in the response packet 91, and notifies it to the interface manager 42 which may be included in the path manager 45. The interface manager 42 prepares a new logical interface of the point-to-point type corresponding to the direct route to the destination end equipment.
In addition, the path manager 45 registers the point-to-point type interface in the routing table 44 by a signal 92 so that the point-to-point type logical interface may indicate that there is a direct route to the destination end equipment.
Thereafter, the data packet 70 addressed to the destination end equipment which has been inputted to the packet transmitter 43 will be transmitted to the destination end equipment by the direct route through the point-to-point type interface with the signals 81, 82 and 83.
As a result, since the point-to-point type logical interface corresponds to the data link layer address of the destination, the network layer address of the destination and the data link layer address of the destination correspond to each other. Accordingly, the address conversion from the network layer address to the data link layer address in the data link layer is not required, and all processes are executed in the network layer. In addition, the way of transmitting the data packet to physical media after the transmission thereof to the interface 47 depends on the media and the transmission function of the data link layer.
[2] Also, in the present invention, an end equipment which works as a receiving destination, as shown in FIG. 1, comprises; a routing table 44 indicating a corresponding relationship between a network layer address of a destination for an inquiry packet 90 (91) which is an input packet and a logical interface, a path manager 45 which determines that the received inquiry packet 90 is addressed to itself and prepares a response packet 85 including its own data link layer address, and a packet transmitter 43 which transmits the response packet 85 (81, 82) to a routing route included in the logical interface 47 retrieved from the routing table 44 with a network layer address of a transmitting source included in the inquiry packet 90 addressed to itself as a key.
FIG. 2 shows an example (1) of the address resolution which uses an end equipment according to the present invention. A logical subnetwork 20 is provided in an NBMA network 10. The logical subnetworks 20_1, 20_2 and the logical subnetworks 20_2, 20_3 are mutually connected with the routers 30_1, 30_2 respectively. The logical subnetworks 20_1, 20_3 are connected to the end equipments 40_1, 40_2, respectively.
An inquiry packet 71 transmitted from the end equipment 40_1 is inputted to the end equipment 40_2 via a routing route 60.
A response packet 72 to the inquiry packet 71 is made in the end system 40_2 and is sent to a routing route 61. The response packet 72 is transmitted to the end equipment 40_1 via the routers 30_1, 30_2.
The NBMA network 10 in FIG. 2 may comprise a broadcast network.
[3] Also, in the present invention, a router which connects a plurality of subnetworks established on the network may comprise; as shown in FIG. 1, a routing table 44 indicating a corresponding relationship between a network layer address of a destination for a packet 90 and a logical interface 47, and a path manager 45 which transmits an inquiry and a response packet which are not addressed to the same path manager to the logical interface of a routing route referring to the routing table 44 with the network layer address of the destination included in a received inquiry packet and a response packet 91 as a key.
Namely, as shown in FIG. 1, when the path manager 45 has detected the received inquiry packet and the response packet 90 (signal 91) having been not addressed to itself, the logical interface 47 of the routing route is obtained with the signal 84 referring to the routing table 44 with the signal 92 with the network layer address of the destination included in the inquiry packet or the response packet 91 as a key.
The path manager 45 sends the inquiry packet or the response packet as output packet signals 95 and 83 through the logical interface.
The operation will now be described referring to the router 30_1 shown in FIG. 2 as follows:
When the router 30_1 inputs the inquiry packet 71 which is not addressed to itself from the routing route 60 (the route from left), the router 30_1 sends the inquiry packet 71 to the routing route 60 (the right route) which the routing table 44 designates.
Also, having received the response packet 72 which is not addressed to itself from the routing route 61 (the route from right), the router 30_1 sends the response packet 72 to the routing route 61 (the left route) which the routing table 44 designates.
It is to be noted that the router may execute the address resolution in the same way as the end equipment by providing the router with an equal function to the end equipment, except that the router relays the inquiry packet and the response packet.
Moreover, the NBMA network 10 in FIG. 2 may comprise a broadcast network.
[4] Also, in the above-mentioned invention [1], the path manager 45 may include a buffer (not shown) for temporarily storing the input packet 70 until the direct route of the data packet 70 is registered in the table 44.
Namely, when there is no buffer, as mentioned above, the transmission is executed via a preset routing route, but it becomes possible to make all of the dada packets 70 wait by using the buffer, and to transmit them to the destination end equipment through the direct route which has been decided in the mean time.
[5] Also, in the present invention, an end equipment which works as a receiving destination 40_2 connected to at least one subnetwork may comprise, as shown in FIG. 1, a path manager 45 which determines that a received inquiry packet 90 (91) is addressed to itself, prepares a response packet including its own data link layer address, and transmits the response packet 95 (83) by using a data link layer address of a source end equipment included in the inquiry packet 90 (91), instead of using the routing table 44.
[6] Also, in the present invention, the subnetwork may be an NBMA network, and as shown in FIG. 1, an end equipment which works as a receiving destination 40_2 may comprise; a signaling manager 50 which sets up a direct path, and a path manager 45 which determines that a received inquiry packet 90 (91) is addressed to itself and prepares a response packet including its own data link layer address.
The path manager 45 requests the signaling manager 50 to call a source end equipment 40_1 by using a data link layer address of the source end equipment 40_1 included in the inquiry packet 90 (91), instead of requesting the transmission of the response packet to the packet transmitter 43.
The signaling manager 50 calls for setting up a virtual connection. The path manager 45 requests the interface manager to prepare a logical interface in the interface 47 for the transmission to the virtual connection set up and may send the response packet through the prepared interface.
FIG. 3 shows an example (2) of the address resolution which uses an end equipment according to the present invention, and the arrangement of the network is the same as that shown in FIG. 2.
The destination end equipment 40_2 receives the inquiry packet 71 through the routing route 60 and prepares a response packet 72 for the inquiry packet 71. In addition, the destination end equipment 40_2 sets up a virtual connection 62 with the destination end equipment 40_1 and transmits the response packet 72 to the end equipment 40_1 through the virtual connection 62.
As a result, it becomes possible to directly transmit the response packet 72 to the end equipment 40_1 at a high speed without passing through the routing route 61 shown in FIG. 2.
[7] Also, in the present invention, as shown in FIG. 1, an end equipment which works as a receiving destination connected to a subnetwork for broadcast may comprise; an interface manager 42 which prepares a logical interface 47 between a network layer and a data link layer, and a path manager 45 which instructs the interface manager 42 to prepare a new logical interface whose destination is a source end equipment by using a data link layer address of the source end equipment included in a received inquiry packet 90 and which transmits a made response packet to the logical interface.
FIG. 4 shows an example (3) of the address resolution which uses an end equipment according to the present invention, wherein the arrangement of the network 10 is the same as that in FIG. 2 except that the network 10 shown in FIG. 2 is not an NBMA network but a broadcast subnetwork and that each of the logical subnetworks 20_1-3 is a VLAN (Virtual LAN).
The end equipment 40_2 which has received the inquiry packet 71 from the routing route 60 prepares the point-to-point type interface 47 for the source end equipment 40_1. The end equipment 40_2 transmits the response packet 72 to the end equipment 40_1 via the direct route 63 through the interface 47.
Thereafter, it becomes possible to directly transmit the packet to the end equipment 40_2 through the new interface 47.
[8] Also, in the above-mentioned invention [1], the logical interface 47 may be defined as one or a plurality of interface managing tables linked with each other composed of at least a logical interface name which is a parameter regarding the interface, its own network layer logical address, a network layer logical address of the destination and the data link layer address.
[9] Also, in the above-mentioned invention [8], the subnetwork may comprise a subnetwork for broadcast, and the data link layer may have a packet transmitter which receives a packet from the logical interface 47 and may transmit the packet by a method which is suitable to various communication media with the logical interface 47 as a key based on the data link layer address of the destination obtained from the interface managing table.
FIG. 5 shows an example (4) of the address resolution which uses an end equipment according to the present invention, and the arrangement of the network 10 is the same as that shown in FIG. 4.
If the network 10 is the Ethernet, for example, the packet transmitter puts the above-mentioned destination data link layer address at the position of a destination MAC address of an MAC header. When the address resolution is executed by using a CSMA/CD (Carrier Sense Multiple Access with Collision Detection) method which is for the media access in the Ethernet, the packet is transmitted on the communication media by broadcast.
[10] Also, in the above-mentioned invention [8], the subnetwork may comprise an NBMA network, and as shown in FIG. 1, may further comprise a signaling manager for setting up a virtual connection directed to a destination end equipment based on the data link layer address of the destination obtained from the interface managing table when the direct route of the destination end equipment does not exist.
FIG. 6 shows an example (5) of the address resolution which uses an end equipment according to the present invention, and the arrangement of the network 10 is the same as that shown in FIG. 2.
When there is found no direct route of the destination end equipment 40_2, the end equipment 40_1 executes a call 63 to the destination end equipment 40_2. The data packet 70 is transmitted to the provided virtual connection 62.
In the above-mentioned invention [1], it is possible to prepare the direct route to the end equipment beforehand by using the data link layer address of the end equipment included in the response packet before receiving the response packet and preparing the interface.
[11], [12] Also, in the above-mentioned invention [1] or [7], an end equipment, as shown in FIG. 7, may comprise a timer manager 48 connected to the interface manager 42. The timer manager 48 has a timer corresponding to each of the logical interfaces and manages the timer. The arrangement in FIG. 7 is the same as that in FIG. 1 except the timer manager 48 is added.
Namely, when the interface manager 42 prepares the logical interface, the timer manager 48 starts the timer. The timer manager 48 clears the value of the timer every time the packet is transmitted through the logical interface 47. When the packet transmission is not executed for a while and when the timer has exceeded a predetermined value, the logical interface is deleted from the interface table.
As a result, by deleting the logical interface prepared before more than a fixed time it becomes possible to avoid using a wrong interface even when the end equipment moves.
[13] In the above-mentioned invention [1], as shown in FIG. 8, a priority controller 49 may be mutually connected to the packet transmitter 43 of the source end equipment by signals 108, 109.
Namely, if both of the routing route and the direct route for the destination end equipment exist, the packet transmitter 43 transmits information 108 included in the received data packet 70 to the priority controller 49. The controller 49 determines to which of the direct route or the routing route the data packet 70 should be transmitted, and notifies the signal 109 to that effect to the packet transmitter 43. The packet transmitter 43 recognizes the interface 47 corresponding to the decided route by the routing table 44, and transmits the input data packet 70.
As a result, the data packet 70 is transmitted to the suitable route.
[14] Also, in the above-mentioned invention [1], as shown in FIG. 1, a user may prepare the interface and executes a user command for registering itself in the router before starting the communication with the user command processor 41. The user command processor 41 instructs the interface manager 42 to prepare the primary interface for the network connected to itself, or demands the preparation of a registration request packet to the path manager 45 through the registration portion 46 by a signal 103.
The path manager 45 instructs the signaling manager 50 of the data link layer to call the router. The signaling manager 50 calls for setting up the routing route. The interface manager 42 prepares the interface corresponding to the routing path. The path manager 45 registers an entry indicating that the router is connected to an ahead of the interface in the routing table 44.
[15] Also, in the above-mentioned invention [1], if the subnetwork may comprise a NBMA network, the routing route and the direct route may comprise a virtual connection.
In the above-mentioned invention [1], it is possible to apply the source end equipment, the destination end equipment and the router to an end equipment connected to the NBMA network or the broadcast network, and a router placed on the boundary of the LIS or VLAN which logically divides these networks.